Computer Systems and Related Methods for Cooling Such Systems

ABSTRACT

Methods for cooling computer systems are provided, in which the computer system has a processor and a fan. An exemplary method comprises: determining a temperature threshold for operating the fan at greater than low speed; determining a temperature of the computer system; and throttling the processor if the temperature corresponds to the temperature threshold for operating the fan at greater than low speed. Systems also are provided.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.10/810,961, filed on Mar. 26, 2004, which is incorporated herein byreference in its entirety.

BACKGROUND

Components of computer systems, such as processors, generate heat duringoperation. Since the performance of such components can be degradedand/or damage can result to these components due to exposure to hightemperatures, the heat generated during operation typically must bedissipated. In this regard, several approaches have been used forcooling computer systems.

By way of example, some computer systems use a fixed cooling solutionthat involves operating a fan to provide a maximum flow of cooling airacross any heat generating components of the computer system.Unfortunately, such a solution tends to create a continuous andsubstantial amount of noise related to the operation of the fan.

Other computer systems implement an active cooling solution that alsoinvolves the use of a fan. However, in contrast to the fixed coolingsolution, this fan is only operated to provide maximum cooling flow,i.e., operated at high speed, when needed. Thus, noise associated withoperation of the fan only increases when the fan is required to providean increased flow of cooling air.

SUMMARY

Systems and methods for cooling computer systems are provided, in whichthe computer system has a processor and a fan. An embodiment of such amethod comprises: determining a temperature threshold for operating thefan at greater than low speed; determining a temperature of the computersystem; and throttling the processor if the temperature corresponds tothe temperature threshold for operating the fan at greater than lowspeed.

Another embodiment of such a method comprises: operating the fan at afirst acoustic level; determining power usage of the computer system;throttling the processor if the power usage corresponds to operating thefan at an increased acoustic level such that the processor is throttledto cool the computer system prior to operating the fan at the increasedacoustic level.

An embodiment of such a computer system comprises a processor, a fan anda temperature-monitoring unit. The fan is operative to provide coolingairflow for reducing a temperature of the processor and has atemperature threshold corresponding to operation of the fan at a speedgreater than low speed. The temperature-monitoring unit is operative todetermine a temperature of the computer system and to throttle theprocessor if the temperature corresponds to the temperature thresholdfor operating the fan at greater than low speed.

Another embodiment of such a computer system comprises apower-monitoring unit that comprises: logic configured to determine atemperature threshold for operating the fan at greater than low speed;logic configured to determine a temperature of the computer system; andlogic configured to throttle the processor if the temperaturecorresponds to the temperature threshold for operating the fan atgreater than low speed.

BRIEF DESCRIPTION OF THE DRAWINGS

The components in the drawings are not necessarily to scale relative toeach other. Like reference numerals designate corresponding partsthroughout the several views.

FIG. 1 is a schematic diagram of an embodiment of a computer system.

FIG. 2 is a flowchart depicting functionality of the power-monitoringunit of FIG. 1.

FIG. 3 is a schematic diagram of another embodiment of a computersystem.

FIG. 4 is a set of graphs depicting various signals provided by theembodiment of FIG. 3.

FIG. 5 is a flowchart depicting an embodiment of a method for cooling acomputer system.

FIG. 6 is a flowchart depicting another embodiment of a method forcooling a computer system.

FIG. 7 is a flowchart depicting another embodiment of a method forcooling a computer system.

DETAILED DESCRIPTION

Computer systems and related methods for cooling such systems areprovided. As will be described in detail here, an exemplary embodimentof such a computer system provides a reduced acoustic output compared toprior art systems. This is because as the power usage, e.g.,temperature, of the computer system increases, the processor isthrottled. Specifically, the processor is throttled to prevent a fan ofthe computer system from operating at a high speed. By throttling theprocessor, power required by the processor is reduced so that theprocessor does not generate as much heat. Typically, this can beaccomplished while providing a negligible impact on system performanceas perceived by a user. Beneficially, by reducing the operatingtemperature of the processor, the fan can be operated at a lower speedwith a lower acoustic output.

Referring now to the drawings, FIG. 1 is a schematic diagram of anembodiment of a computer system 100. Computer system 100 includes aprocessor 102, e.g. a central processing unit, and a fan 104 that isoperative to provide a cooling flow of air for cooling processor 102.Fan 104 is a variable speed fan, e.g., a continuously variable fan,although, in other embodiments, a single-speed fan that is operatedintermittently could be used.

Also included in computer system 100 is a power-monitoring unit 106.Power-monitoring unit 106 is operative to determine a power usagecorresponding to the computer system 100. In particular, thepower-monitoring unit 106 receives power usage information associatedwith processor 102. In response to receiving the power usageinformation, the power-monitoring unit 106 determines whether processor102 should be throttled. That is, a determination is made as to whetherthe processor 102 should be operated in a reduced performance and powerconsumption mode. If the processor is to be throttled, thepower-monitoring unit 106 provides a throttle control signal toprocessor 102 for controlling throttling of the processor. Varioustechniques for throttling a processor are known, such as described inU.S. Pat. No. 6,029,251, which is incorporated by reference herein;therefore, a more detailed description of throttling will not beprovided here.

In the embodiment of FIG. 1, power-monitoring unit 106 attempts tocontrol the power usage of processor 102 by throttling the processorprior to the computer system attaining a temperature that causes fan 104to operate at high speed. Throttling the processor in this mannerprevents the fan from generating noise at an increased acoustic levelcompared to the acoustic level generated when the fan is operating atlow speed.

FIG. 2 is a flowchart depicting functionality of the embodiment of thepower-monitoring unit of FIG. 1. As shown in FIG. 2, the functionality(or method) may be construed as beginning at block 202, where powerusage of the computer system, e.g., power usage of a processor of thecomputer system, is determined. In block 204, a determination is made asto whether the power usage corresponds to a threshold for operating thefan at a higher speed. If it is determined that the power usagecorresponds to the threshold for operating the fan at the higher speed,the processor is throttled as depicted in block 206. If, however, thepower usage does not correspond to the threshold, the process may returnto block 202 and proceed as described before.

FIG. 3 is a schematic diagram of another computer system, specifically,a computer system 300. Computer system 300 includes a processor 302 anda fan 304. Computer system 300 also includes a type of power-monitoringunit, in particular, a temperature-monitoring unit. Thetemperature-monitoring unit 306 is considered a type of apower-monitoring unit because temperature typically corresponds to powerusage of a computer system.

In operation, temperature information is provided from a temperaturesensor 308, e.g., a thermal diode, of the processor to thetemperature-monitoring unit 306. In response to the temperatureinformation, temperature-monitoring unit 306 provides a pulse widthmodulation (PWM) output to the processor for controlling throttling ofthe processor. Specifically, the PWM output is provided to thePROC_HOT_SIGNAL input of the processor 302. PWM output will be describedin greater detail later with respect to FIG. 4. Note that in theembodiment of FIG. 3, the PWM output is provided first to an inverter310 and then to processor 302.

The temperature-monitoring unit 306 provides a fan speed control signalto fan 304. Thus, in this embodiment, the temperature-monitoring unitcontrols processor throttling and fan speed. For example, if throttlingof the processor 302 is unable to maintain the temperature at or below ahigh temperature threshold, the fan speed control signal provided by thetemperature-monitoring unit can adjust the fan to operate at a higherspeed. Typically, however, the temperature-monitoring unit ensures thatthrottling is accomplished prior to allowing the fan to operate at aspeed other than low speed, thereby maintaining the acoustic level ofthe fan at a low level.

FIG. 4 depicts a set of graphs related to the PWM output of thetemperature-monitoring unit 306. Specifically, the first graph depictsthe PMW output of the temperature-monitoring unit when the temperatureinformation corresponds to a temperature below an established lowtemperature threshold. As can be seen, when the temperature is below thelow temperature threshold, the voltage of the PWM output is high. Incontrast, when the temperature information corresponds to a temperatureabove a high temperature threshold, the PMW output is a low voltage.Moreover, when the temperature is between the high temperature and lowtemperature thresholds, the PMW output alternates between the highvoltage and low voltage levels with the duration of the voltage levelspresent in the waveform corresponding to the temperature. In the exampledepicted, the output corresponds to a temperature half way between thehigh temperature threshold and the low temperature threshold, thus, thevoltage of the waveform is high for fifty percent of the time and lowfor the other fifty percent.

The graphs to the right side of FIG. 4 depict the output of the inverter310. The original PWM output is inverted because throttling of theprocessor is active when a low voltage PROC_HOT_SIGNAL is received. Thatis, a sensed high temperature produces a high output PWM signal, whichis then inverted and provided as a low voltage signal to cause theprocessor to be throttled.

FIG. 5 is a flowchart depicting functionality of another embodiment of acomputer system. As shown in FIG. 5, the process may be construed asbeginning at block 502, where a high temperature limit of a processor ofthe computer system is determined. In block 504, temperatures at whichvarious fan speeds are to be actuated are set. By way of example, withrespect to a two-speed fan, the temperature at which the fan is totransition from low speed operation to high speed operation can be set.In block 506, a determination is made as to whether the system is tooperate in a reduced acoustic mode. If the system is not to operate inthe reduced acoustic mode, the process may proceed to block 508, wherethe fan is enabled to control the processor temperature. If, however,the system is to operate in a reduced acoustic mode, the process mayproceed to block 510.

In block 510, a temperature corresponding to the processor isdetermined. Then, as depicted in block 512, a determination is made asto whether the temperature corresponds to the previously determined hightemperature limit of the processor. If the temperature is not high, theprocess may return to block 510. If, however, the temperature isdetermined to be high, the process may proceed to block 514, where theprocessor is throttled. After throttling the processor, the process alsomay return to block 510 and proceed as described before.

Note that various techniques can be used for determining whether thesystem is to operate in a reduced acoustic mode. For example, thedetermination could be made in response to a user input provided duringBIOS setup of the computer system.

Power monitoring units, e.g. power-monitoring unit 106, can beimplemented in software, firmware, hardware, or a combination thereof.When implemented in hardware, such a unit can be implemented with any ora combination of various technologies. By way of example, the followingtechnologies, which are each well known in the art, can be used: adiscrete logic circuit(s) having logic gates for implementing logicfunctions upon data signals, an application specific integrated circuit(ASIC) having appropriate combinational logic gates, a programmable gatearray(s) (PGA), and a field programmable gate array(s) (FPGA).

In alternative embodiments, a power-monitoring unit could be implementedin software as an executable program(s). When implemented in software,it should be noted that the power-monitoring unit can be stored on anycomputer-readable medium for use by or in connection with anycomputer-related system or method. In the context of this document, acomputer-readable medium is an electronic, magnetic, optical, or otherphysical device or means that can contain or store a computer programfor use by or in connection with a computer-related system or method. Apower-monitoring unit can be embodied in any computer-readable mediumfor use by or in connection with an instruction execution system,apparatus, or device, such as a computer-based system,processor-containing system, or other system that can fetch theinstructions from the instruction execution system, apparatus, or deviceand execute the instructions.

In the context of this document, a “computer-readable medium” can be anymeans that can store, communicate, propagate, or transport the programfor use by or in connection with the instruction execution system,apparatus, or device. The computer readable medium can be, for examplebut not limited to, an electronic, magnetic, optical, electromagnetic,infrared, or semiconductor system, apparatus, device, or propagationmedium. More specific examples (a nonexhaustive list) of thecomputer-readable medium would include the following: an electricalconnection (electronic) having one or more wires, a portable computerdiskette (magnetic), a random access memory (RAM) (electronic), aread-only memory (ROM) (electronic), an erasable programmable read-onlymemory (EPROM, EEPROM, or Flash memory) (electronic), an optical fiber(optical), and a portable compact disc read-only memory (CDROM)(optical). Note that the computer-readable medium could even be paper oranother suitable medium upon which the program is printed, as theprogram can be electronically captured, via for instance opticalscanning of the paper or other medium, then compiled, interpreted orotherwise processed in a suitable manner if necessary, and then storedin a computer memory.

It should be noted that, in some alternative implementations, thefunctions noted in the various blocks of this and/or other flowchartsdepicted in the accompanying disclosure may occur out of the orderdepicted. For example, two blocks shown in succession in FIG. 5 may beperformed concurrently.

FIG. 6 is a flowchart depicting another embodiment of a method forcooling a computer system. In particular, the computer systemincorporates a processor and a fan. As shown in FIG. 6, the method maybe construed as beginning at block 610, where a temperature thresholdfor operating the fan at greater than low speed is determined. At block620, a temperature of the computer system is determined. At block 630,the processor is throttled if the temperature corresponds to thetemperature threshold for operating the fan at greater than low speed.

FIG. 7 depicts another embodiment of a method for cooling a computersystem. Specifically, this embodiment also involves a computer systemthat includes a processor and a fan. As shown in FIG. 7, the method maybe construed as beginning at block 710, where the fan is operated at afirst acoustic level. At block 720, power usage of the computer systemis determined. At block 730, the processor is throttled if the powerusage corresponds to operating the fan at an increased acoustic levelsuch that the processor is throttled to cool the computer system priorto operating the fan at the increased acoustic level.

It should be emphasized that many variations and modifications may bemade to the above-described embodiments. All such modifications andvariations are intended to be included herein within the scope of thisdisclosure and protected by the following claims.

1.-22. (canceled)
 23. A method for cooling a computer system, thecomputer system having a processor and a fan, said method comprising:operating the fan at a first acoustic level; determining power usage ofthe computer system; and throttling the processor if the power usagecorresponds to operating the fan at an increased acoustic level suchthat the processor is throttled to cool the computer system prior tooperating the fan at the increased acoustic level.
 24. The method ofclaim 23, further comprising: operating the fan at the increasedacoustic level if the throttling is inadequate to maintain thetemperature of the computer system below a temperature threshold foroperating the fan at the increased acoustic level.
 25. The method ofclaim 23, wherein determining the power usage of the computer systemcomprises determining a temperature of the computer system.
 26. Themethod of claim 25, wherein determining the temperature of the computersystem is performed using a thermal diode.
 27. The method of claim 23,wherein: the operating, determining and throttling are associated with areduced-acoustic mode of operation; and the method additionallycomprises: operating the computer system in a normal-acoustic mode ofoperation in which the fan is operated at the increased acoustic levelfor cooling the computer system instead of throttling the processor. 28.The method of claim 23, wherein throttling the processor comprisesproviding a pulse width modulated signal to the processor.
 29. Acomputer system comprising: a processor; a fan operative to providecooling airflow for reducing a temperature of the processor, the fanhaving a temperature threshold corresponding to operation of the fan ata speed greater than low speed; and a temperature-monitoring unitselectively operative in one of a reduced-acoustic mode and anormal-acoustic mode such that: in the normal-acoustic mode, thetemperature-monitoring unit attempts to control the temperature of thecomputer system by adjusting the speed of the fan; and in thereduced-acoustic mode, the temperature-monitoring unit attempts tocontrol the temperature of the computer system by throttling theprocessor.
 30. The system of claim 29, wherein, in the normal-acousticmode, if the temperature-monitoring unit is unable to control thetemperature of the computer system by adjusting the speed of the fan,the temperature-monitoring unit also throttles the processor.
 31. Thesystem of claim 29, wherein, in the reduced-acoustic mode, if thetemperature-monitoring unit is unable to control the temperature of thecomputer system by throttling the processor, the temperature-monitoringunit also adjusts the speed of the fan.
 32. The system of claim 29,wherein: the processor has a temperature sensor operative to generate asignal indicative of a temperature of the processor; and thetemperature-monitoring system receives the signal generated by thetemperature sensor for determining the temperature of the computersystem.
 33. The system of claim 32, wherein the temperature sensorcomprises a thermal diode.
 34. The system of claim 29, wherein thetemperature-monitoring unit throttles the processor by providing asignal corresponding to a pulse width modulation output of thetemperature-monitoring unit to the processor.
 35. The system of claim34, further comprising: an inverter arranged to receive the pulse widthmodulation output of the temperature-monitoring unit such that theprocessor receives the inverse of the pulse width modulation output. 36.A computer system comprising: a processor; a fan for cooling theprocessor; means for determining power usage of the computer system; andmeans for throttling the processor if the power usage corresponds tooperating the fan at an increased acoustic level such that the processoris throttled to cool the computer system prior to operating the fan atthe increased acoustic level.